The present invention relates to a vehicular brake control system.
A brake control system is exemplified by a Japanese Patent Application Unexamined Open No. Sho. 60-78847 published on May 4, 1985 (which corresponds to U.S. pat. application Ser. No. 655,553 filed on Sept. 28, 1984 and corresponds to EPC Patent Application file No. 84 111 721.1 filed on Oct. 1, 1984, and both U.S. and EPC cases have been abandoned).
In the above-identified Patent document, the brake control system controls an output of a brake booster in a brake system so that a relationship between a depression force imposed on a brake pedal and braking deceleration rate is maintained constant. More specifically; the brake control system disclosed in the above-identified Patent document includes: (a) a brake pedal; (b) first means for applying a braking force to the vehicle when the brake pedal is depressed; (c) a power booster for enhancing the braking force to an adjustable degree; (d) second means for sensing the depression force imposed on the brake pedal; (e) third means for determining a desired rate of deceleration of the vehicle on the basis of the sensed depression force; (f) fourth means for sensing the actual rate of deceleration of the vehicle; (g) fifth means for comparing the desired and actual deceleration rates; and (h) sixth means for increasing and decreasing the degree of enhancement of the braking force when the actual deceleration rate is less than and greater than the desired deceleration rate, respectively.
In the above-described brake control system, the braking force and braking deceleration rate can be fixed. However, since converting the output from the brake power booster into a hydraulic pressure starting from a master cylinder and ending at a wheel cylinder is carried out in a hydraulic circuit which is on the output side of the brake booster, the relationship changes between the braking force applied to the brake pedal and brake stroke due to influence derived from the hydraulic circuit side. Consequently, the brake control system gives a driver of the vehicle a sense of incompatibility between the force applied to the brake pedal and the brake stroke.